Campylobacter, Helicobacter, and Arcobacter spp. are examples of common human and animal pathogens (Thomas, C. A. et al., 1966). Although the pathogenicity of such bacteria has long been known, their phylogenetic relationships, isolation, detection, identification, and classification by traditional biochemical tests, have been variable and difficult. This is largely due to their fastidious growth requirements, inability to ferment carbohydrates, and diverse growth characteristics which vary, not only between genera and species, but also within species. Thus, their large phenotypic variations have made biochemical tests unreliable as a sole method for identifying and differentiating these bacteria.
Many of the species in the genera Helicobacter and Arcobacter were once classified under the genus Campylobacter. However, the phylogenetic relationships of these bacteria have been reevaluated based on information from DNA-DNA hybridization, 23S rRNA-DNA hybridization (Vandamme et al., 1991; Vandamme et al., 1993), and partial 16S rRNA sequences (Li et al., 1993; Patton et al., 1991; Totten et al., 1987). These phylogenetic studies have led to the formation of the current classification of the Campylobacter and Vibrio organisms into Campylobacter, Helicobacter, and Arcobacter.
Other than the conventional biochemical tests, alternative methods based on molecular and genetic approaches, have been proposed to improve the identification and differentiation of these bacteria to the species level. These methods include serology (Hebert et al., 1983; Penner, J. L., 1988), enzymology (Elharrif, Z. and Megraud, F., 1986; Paster et al., 1991), cellular fatty acid compositions (Goodwin et al., 1985), electrophoretic protein patterns (Costas et al., 1987; Penner, J. L., 1988), random PCR-DNA fingerprinting (Eyers et al., 1993; Giesendorf et al., 1993; Giesendorf et al., 1994; and Vandamme et al., 1992), and DNA-DNA hybridization (Macario, A. J. L. and Macario, E. C. de. (eds.), 1990; and Penner, J. L., 1988). A highly specific DNA-DNA hybridization method is oligo hybridization. By varying hybridization conditions such as ionic concentration and temperature, oligo probes can detect single nucleotide sequence differences (Lee/Lane, 1992).